首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1326245篇
  免费   95496篇
  国内免费   2871篇
耳鼻咽喉   19697篇
儿科学   40143篇
妇产科学   38651篇
基础医学   185706篇
口腔科学   39850篇
临床医学   111848篇
内科学   259701篇
皮肤病学   30136篇
神经病学   105693篇
特种医学   53597篇
外国民族医学   435篇
外科学   207366篇
综合类   30968篇
一般理论   436篇
预防医学   91359篇
眼科学   31267篇
药学   99697篇
  2篇
中国医学   2948篇
肿瘤学   75112篇
  2018年   11720篇
  2015年   11866篇
  2014年   16683篇
  2013年   25235篇
  2012年   33007篇
  2011年   34865篇
  2010年   20728篇
  2009年   20225篇
  2008年   33506篇
  2007年   36632篇
  2006年   37187篇
  2005年   35971篇
  2004年   35047篇
  2003年   33990篇
  2002年   33492篇
  2001年   63530篇
  2000年   65159篇
  1999年   55028篇
  1998年   13851篇
  1997年   12605篇
  1996年   12102篇
  1995年   12129篇
  1994年   11394篇
  1992年   42703篇
  1991年   41266篇
  1990年   40536篇
  1989年   39527篇
  1988年   36926篇
  1987年   36391篇
  1986年   34875篇
  1985年   33091篇
  1984年   24782篇
  1983年   20982篇
  1982年   12605篇
  1981年   11502篇
  1980年   10706篇
  1979年   23864篇
  1978年   17018篇
  1977年   14761篇
  1976年   13331篇
  1975年   15216篇
  1974年   18040篇
  1973年   17534篇
  1972年   16790篇
  1971年   15698篇
  1970年   14874篇
  1969年   14320篇
  1968年   13440篇
  1967年   11992篇
  1966年   11242篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Objective: Hepatocellular carcinoma (HCC) microenvironment has been recognized as a key contributor for cancer progression, metastasis, and drug resistance. The crosstalk between tumor cells, the vascular endothelial growth factor (VEGF), and the chemokine (C-C motif) ligand 2 (CCL2) signaling networks mediates immunoinhibitory impact and facilitates tumor angiogenesis. The current investigation aimed at exploring the potent anti-cancer activity of the newly designed nano-based anti-cancer therapy comprising anti-VEGF drug, avastin (AV), and CCR2 antagonist (CR) to counteract HCC and tracking its mode of action in vivo. Methods: The prepared AV, CR, and AVCR nanoprototypes were characterized by nanoscale characterization techniques in our previous work. Here, they are applied for unearthing their anti-cancer properties / mechanisms in hepatic cancer-induced rats via analyzing protein levels and genetic expression of the elements incorporated in the angiogenesis, apoptosis, and metastasis signalling pathways. Results: The present results revealed a significant down-regulation in the angiogenesis, survival and metastasis indices along with up-regulation in the pro-apoptotic mediators upon treatment of hepatic cancer-bearing rats with the novel synthesized nanomaterials when compared with the untreated counterparts. We showed across HCC model that anti-VEGF in combination with CCR2 antagonism therapy leads to sensitization and enhanced tumor response over anti-VEGF or CCR2 antagonism monotherapy, particularly in its nanoscale formulation. Conclusion: The present approach provides new mechanistic insights into the powerful anti-hepatic cancer advantage of the novel nanoprototypes which is correlated with modulating critical signal transduction pathways implicated in tumor microenviroment such as angiogenesis, apoptosis and metastasis. This research work presents a substantial foundation for future studies focused on prohibiting cancer progression and recovery by targeting tumor microenviroment.  相似文献   
3.
Graefe's Archive for Clinical and Experimental Ophthalmology - Ferromagnetic foreign bodies (FFB) present during magnetic resonance imaging (MRI) explorations can lead to tissue injury due to...  相似文献   
4.
5.

Background

Advanced low-grade ovarian carcinoma (LGOC) is difficult to treat. In several studies, high estrogen receptor (ER) protein expression was observed in patients with LGOC, which suggests that antihormonal therapy (AHT) is a treatment option. However, only a subgroup of patients respond to AHT, and this response cannot be adequately predicted by currently used immunohistochemistry (IHC). A possible explanation is that IHC only takes the ligand, but not the activity, of the whole signal transduction pathway (STP) into account. Therefore, in this study, the authors assessed whether functional STP activity can be an alternative tool to predict response to AHT in LGOC.

Methods

Tumor tissue samples were obtained from patients with primary or recurrent LGOC who subsequently received AHT. Histoscores of ER and progesterone receptor (PR) were determined. In addition, STP activity of the ER STP and of six other STPs known to play a role in ovarian cancer was assessed and compared with the STP activity of healthy postmenopausal fallopian tube epithelium.

Results

Patients who had normal ER STP activity had a progression-free survival (PFS) of 16.1 months. This was significantly shorter in patients who had low and very high ER STP activity, with a median PFS of 6.0 and 2.1 months, respectively (p < .001). Unlike ER histoscores, PR histoscores were strongly correlated to the ER STP activity and thus to PFS.

Conclusions

Aberrant low and very high functional ER STP activity and low PR histoscores in patients with LGOC indicate decreased response to AHT. ER IHC is not representative of functional ER STP activity and is not related to PFS.  相似文献   
6.
7.
8.

Background

Septic shock is often treated with aggressive fluid resuscitation leading to profound fluid overload. The assessment of fluid status relies on suboptimal measures making treatment difficult. Bioelectrical impedance analysis is an alternative but the validity is unclear. The aim of this study was to determine the validity of bioelectrical impedance analysis for fluid measures in patients with septic shock.

Methods

Single-center, prospective observational cohort study. We included adult ICU patients with septic shock. We evaluated the agreement between measures on the left and right side of the patient and measures 1 h apart by two bioelectrical impedance devices. Results are presented as Bland Altman plots with 95% Limits of Agreements (LoA) and as correlations between bioelectrical impedance analysis results and clinical markers of fluids.

Results

Forty-nine patients were included. The agreement between measures on the left and the right side of the patient and after 1 h was overall without bias, but with wide LoA's. Fluid overload 1 h apart showed the most narrow 95% LoA (−2.4–2.9 L). The same wide limits of agreements were observed when comparing devices. For example, total body water with 95% LoA of −14.8 –16.7 L. Correlations between bioelectrical impedance analysis and clinical measures were low but statistically significant.

Conclusions

In patients with septic shock bioelectrical impedance analysis had no systematic errors or bias, but wide limits of agreement, indicating that the devices have a large and uncorrectable random error. Fluid status by bioelectrical impedance analysis is not sufficiently accurate to guide treatment in this group of patients.  相似文献   
9.
Peng  L. Q.  Wu  X. X.  Chen  G.  Cai  H. Z.  Tang  Y. P.  Chen  Q. Y.  Chen  X. Y. 《Bulletin of experimental biology and medicine》2022,173(3):335-340
Bulletin of Experimental Biology and Medicine - This study aimed to explore the effects of Wenyang Zhenshuai granules (WZG) on the morphology of cardiomyocytes, cell viability, and the expression...  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号